This project is an investigation of gonadal hormone influences on human sexually-dimorphic behavior in children with congenital' adrenal hyperplasia (CAH), a genetic disease which results in increased prenatal levels of androgen. It is a continuation of earlier studies, which demonstrated hormonal influences on play behavior, aggression, and spatial ability, and represents the first longitudinal study of the behavioral consequences of elevated prenatal androgen exposure. The purpose of the proposed study is to elaborate further the behavioral mechanisms through which gonadal hormones masculinize behavior, the developmental consequences of hormonal influences on early toy choices, and the ways in which social factors modify the expression of sex-typed behaviors. The aims are three-fold: (l) to continue to follow-up hormone-exposed and control children already tested on various aspects of sex-typed behavior to see if these hormone-exposed girls continue to have increased interest in masculine activities, and, if so, to determine whether hormonal influences on these activities and spatial ability are the result of increased play with boys' toys in early childhood; (2) to study whether motor skills are influenced by prenatal androgen, and, if so, to determine if relative superiority in gross vs. fine motor skills (alone and in combination with high motor activity) accounts for participation in masculine activities; (3) to assess whether children's preference for same-sex playmates is influenced by prenatal androgen, and, if so, to determine whether this preference is predictable from toy preference or other sex-typed behavior. Subjects include 61 CAH girls and 46 CAH boys aged 3-15, and 109 sex- and age-matched relative controls. Subjects will be tested on two occasions on measures of sex-typed activities, peer preferences, motor skills, motor activity, and cognitive abilities. The longitudinal nature of the study allows examination of relationships between early childhood toy play and later sex-typed activities and abilities. Results from this study will provide information about hormonal influences on the development of specific behaviors that are both socially and educationally relevant. They will also provide information than can be used in the medical management and counseling of patients with CAH, and children who are exposed to masculinizing drugs in utero because of maternal treatment for infertility problems.